(1) Some of the reasons why a successful procedure for the routine preparation of pure blowfly calliphorin has not yet been achieved have become apparent. This protein in intrinsically unstable, and spontaneously breaks down into lower Mol. Wt. components. (2) The earlier qualitative observations that molting hormone (Beta-ecdysone) inhibits fat body synthesis of calliphorin in vitro has been investigated quantitatively. (3) The kinetics of phagocytosis by larval blood hematocytes in vitro has been studied employing a new microassay. These cells contain a fraction of the blood calliphorin. (4) The changing titers of several free monosaccharides during embryogenesis of the tick Dermacentor andersoni have been measured. BIBLIOGRAPHIC REFERENCES: Protzel, A., Sridhara, S. and Levenbrook, L.: Ribosomal replacement and degradation during metamorphosis of the blowfly, Calliphora vicina. Insect Biochem. 6: 571-578, 1976. Protzel, A. and Levenbook, L.: Rate of rRNA synthesis during metamorphosis of the blowfly, Calliphora vicina. Insect Biochem. 6: 631-635, 1976.